Linux in the Real World

If you have ever considered starting your own Internet Services Provider business with Linux, Todd gives you both an introduction to the subject and a quiz to help you decide if you really want to start.

Ever since the opening of the Internet to
commercial development a few years ago, many an individual has made
a living for himself by leasing a connection to the global network,
establishing a local network, and tacking up his siihingle as an
Internet Service Provider (ISP). ISPs, from the mighty MCI down to
the most humble Mom and Pop basement organizations, offer exactly
the same thing—a direct connection to the Internet. Smaller
businesses do this mostly via PPP connections over modems, whereas
larger ISPs tend to stick to leased-line dedicated connections.

Although this might sound daunting at first, the actual
process is not impossible, even for a single individual of limited
resources. The most pressing obstacle in the past has been that the
resources needed to offer ISP-like services—not merely PPP
connections but also e-mail, Usenet, and FTP/WWW hosting—have only
been available in the form of high-end (and high-cost) Unix
workstations. This translated into considerable cost for the
budding entrepreneur.

The other traditional problem has been that the system- and
network-administration skills needed to offer such services could
only be gained on one of these high-priced workstations, creating a
chicken-or-the-egg dilemma, whereby if you did not already have
access to these machines through work or school, your main capital
investment would have to sit idle for six months to a year while
you tried to learn how to run it.

The ubiquitous nature of Intel-x86-based personal computers,
the strength of their networking capabilities and, most of all,
free operating systems such as Linux brought this sad state of
affairs to an end. With its traditions of laissez-faire development
and absolutely free access, Linux offers two qualities essential to
the upstart ISP. The first of these is minimal cost. The second,
and the more important, is the ability to learn
all the essentials of network administration
on an operating system which refuses to withhold any secrets from
you.

It is hard to reinforce this latter aspect of Linux enough.
As an independent Internet Service Provider, your job is network
management. If your machines are not routing traffic properly,
you must understand why and be able to fix it.
If your Usenet feed is clogging your system,
you must be able to diagnose the problem and
fix it. If your DNS is not spitting out IP numbers properly, it is
your problem, and yours alone. Microsoft
technical support will not come down and help you figure out why.
Sprint or MCI will not drop what they are doing to help you out,
even if you are their customer. Good consultants (other than the
author) are notoriously hard to find and (including the author) are
horribly expensive.

Linux is the operating system of choice
for ISPs, because it fulfills the number one requirement for an
ISP's OS. You must be able to diagnose problems, and you must know
enough about your system's operation to be able to fix the problems
which will plague you, no matter what OS you
choose. This, combined with the huge range of software available
for Linux, make it the hands-down winner.

This is not to say that Linux is perfect, and indeed, there
are several problems with Linux in an ISP environment. This article
should help by offering a roadmap, showing both obstacles and
bypasses to help you in your journey. It does not offer advice on
how to connect to the Internet, but rather concentrates on using
Linux to offer ISP services.

Getting Started: Hard(ware) Choices

Your first step is deciding on a hardware base. What kind of
machines will you run? How many of them will you have? What
peripheral equipment will you need? You should have good answers to
all of these questions before you buy any
hardware.

In the past, the platform decision was easy. If you ran
Linux, you used an Intel-based or Intel-clone 386 or greater
machine. With the recent enhancements to Linux for the Sparc, MIPS,
and DEC Alpha, this choice is a little more clouded. Red Hat and
others are coming out with full-fledged CD-ROM distributions for
these higher-powered machines. While these are in the early stages
of development and I do not recommend them (yet), the
price-to-performance edge of these machines, especially the DEC
Alpha, means you should keep them in mind as a real option,
especially for upgrading your system down the road. For startups,
though, x86 machines are usually the way to go.

If you are going to concentrate on dial-up business, you will
need modems. Modems can be one of your worst nightmares, and you
should shop carefully. However, the modem issue is not
Linux-specific. With V.34 finally having settled down to a
well-established standard, most modems will do the job, and many
people suggest shopping for price. Nonetheless, doing your homework
by reading reviews and soliciting feedback on Usenet can pay off
many times over. Just think about dedicating hundreds of man-hours
and thousands of dollars to modems that refuse to work, and ask
yourself if the extra initial effort might be worth it.

Of course, standard PCs can handle a pair of modems at best.
How do you connect all of these modems to your PC? The answer is
through one of the many port-servers (also known as terminal
servers) available on the open market. Port servers connect to your
modems with built-in serial ports and forward data back and forth
between them and your computer, usually over a network.
Alternatively, you can use an “intelligent serial board” which
connects the modems directly to a PC. A good review of intelligent
serial boards can be found in the June, 1995 issue of
Linux Journal on page 46. Remember to include
a port server or intelligent serial board in your plans.

Then there is your network itself. Unless you plan to fulfill
all of your requirements with one machine (usually not a good
idea), you will need a network to connect your machines. While Fast
Ethernet, FDDI, and ATM are all options, plain vanilla 10 Mbps
Ethernet is usually the way to go. I recommend 10-base-T
(twisted-pair 4-conductor cable with a hub) over 10-base-2 (coaxial
wire with T-connectors and terminators). 10b2 is simply not
reliable enough to avoid service disruptions as you remove machines
from the network, rearrange your network with expansion, and trip
over the network cable. If you decide on the 10bT route, remember
to equip all of your machines with Ethernet cards (anywhere from
$30 to $300 each) and buy an Ethernet hub (between $400 and $1500).
The NET-2-HOWTO includes an excellent discussion of the merits of
the various ethernet cards; ISA bus ne2000 clones offer an easy and
very inexpensive solution.

Presumably, you have arranged an Internet connection, either
through one of the nationwide services such as Sprint, MCI, and
ANS, or through another regional ISP. Traditionally, this
connection is done via a dedicated router. Cisco Systems makes the
best high-speed routers available, but they are usually overkill
for connections of T1 speed or less. Livingston routers are a
particular favorite among the Linux community, and other options
also exist. An increasingly popular option is to make your own
router out of a Linux-based PC, using a T1-interface card from a
manufacturer like Enhanced Technologies. If you have an ISDN
connection, then you can use your Linux box as a router too,
through an ISDN terminal adapter from 3COM, Boca, Motorola, and
others.

Finally, you have to decide how many Linux machines you will
need. This all depends on how you have designed your network. There
are two big mistakes that people make. On the one hand, some assume
that every little network function needs a dedicated server. “We
have to have a dedicated DNS, a dedicated web server, a dedicated
FTP server, a dedicated mail server...” This can become very
expensive, very quickly, and unnecessarily so. On the other hand, I
have seen people make the mistake of cramming news, mail, PPP, and
web service all on one machine, which is so slow that their
customers leave as fast as they come in the door.

What hardware will younee and how should it be connected? How
much will it cost? Through the rest of this article, we'll look at
the service you can offer as an ISP and what kind of setup you'll
need to do provide it.

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